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Using CT to evaluate mediastinal great vein invasion by thymic epithelial tumors: measurement of the interface between the tumor and neighboring structures



For thymic epithelial tumors, simple contact with adjacent structures does not necessarily mean invasion. The purpose of our study was to develop a simple noninvasive technique for evaluating organ invasion using routine pretreatment computed tomography (CT).


This retrospective study analyzed the pathological reports on 95 mediastinal resections performed between January 2003 and June 2020. Using CT images, the length of the interface between the primary tumor and neighboring structures (arch distance; Adist) and maximum tumor diameter (Dmax) was measured, after which Adist/Dmax (A/D) ratios were calculated. Receiver operating characteristic (ROC) curves were used to analyze the Adist and A/D ratios.


An Adist cut-off of 37.5 mm best distinguished between invaded and non-invaded mediastinal great veins based on ROC curves. When Adist > 37.5 mm was used for diagnosis of invasion of the brachiocephalic vein (BCV) or superior vena cava (SVC), the sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and area under the ROC curve for diagnosis of invasion were 61.9%, 92.5%, 81.25%, 82.2%, 81.97%, and 0.76429, respectively. Moreover, there were significant differences between BCV/SVC Adist > 37.5 mm and ≤ 37.5 mm for 10-year relapse-free survival and 10-year overall survival (p < 0.01).


When diagnosing invasion of the mediastinal great veins based on Adist > 37.5 mm, we achieved a higher performance level than the conventional criteria such as irregular interface with an absence of the fat layer. Measurement of Adist is a simple noninvasive technique for evaluating invasion using CT.

Key Points

Simple contact between the primary tumor and adjacent structures on CT does not indicate direct invasion.

Using CT images, the length of the interface between the primary tumor and neighboring structures (arch distance; Adist) is a simple noninvasive technique for evaluating invasion.

Adist > 37.5 mm can be a supportive tool to identify invaded mediastinal great veins and surgical indications for T3 and T4 invasion by thymic epithelial tumors.

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Fig. 5


A/D ratio:

The Adist-to-Dmax ratio


Length of the interface between the primary tumor and neighboring structures


The areas under the ROC curves


Brachiocephalic vein


Maximum tumor diameter




[18F] Fluoro-2-deoxy-D-glucose-positron emission tomography


International Association for the Study of Lung Cancer


International Thymic Malignancies Interest Group


National Comprehensive Cancer Network


Negative predictive value


Overall survival


Positive predictive value


Relapse-free survival

ROC curves:

Receiver operating characteristic curves


The standardized uptake value


Superior vena cava


Union for International Cancer Control


Video-assisted thoracic surgery


World Health Organization


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The authors are grateful to Profs. Hiroshi Nanjo (Department of pathology, Akita University Graduate School of Medicine) and Akiteru Goto (Department of Cellular and Organ Pathology, Akita University Graduate School of Medicine) for suggesting pathological diagnoses.


The authors state that this work has not received any funding.

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Correspondence to Kazuhiro Imai.

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The scientific guarantor of this publication is Yoshihiro Minamiya.

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Kuriyama, S., Imai, K., Ishiyama, K. et al. Using CT to evaluate mediastinal great vein invasion by thymic epithelial tumors: measurement of the interface between the tumor and neighboring structures. Eur Radiol 32, 1891–1901 (2022).

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  • Mediastinal neoplasms
  • Thymic epithelial tumor
  • Neoplasm invasiveness
  • Vena cava, superior
  • Brachiocephalic veins